The invention relates to a bearing system for a turntable with stepping drive, having a table plate journaled on the top of a housing, and having a plurality of driving pins disposed all on the same diameter and projecting from its bottom at uniform angular distances and engaging a groove in a motor-driven cylinder journaled in the housing, the shape of the groove determining the characteristic of the rotation of the table plate.
Stepping turntables of this kind are used in many fields of industrial technology whenever, for example, workpieces are carried successively step by step to various working stations where they are held while being worked, and then must be passed on to the next working station, the working stations being arranged around the table with a uniform angular spacing. The holding means or vises for the workpieces are then mounted on the stepping turntable where they must be held strongly and as free as possible from movement for the achievement of high accuracy. At least in the case of comparatively large units, so-called "wire ball bearings" are used as a rule, in which the bails roll on hardened steel wire rings which thus form the races of the ball bearing. These wire ball bearings have proven useful for heavily loaded rotary bearings of great diameter. In the turntables here in question the configuration has formerly been such that the circularly defined table plate was provided on its outer circumference with a circumferential groove to receive the two wire rings forming the table-side races of the ball bearings, while the wire rings forming the races on the housing side were disposed in the wall of a recess in the housing accommodating the circumference of the turntable on the one hand, and in the circumferential wall facing the turntable plate of a bearing mounting and adjusting ring screwed to the face of the housing. Removing the mounting and adjusting ring by unscrewing it from the housing then permits the bearing to be removed and enables the turntable plate to be lifted away from the turntable housing; then the bearing clearance can be adjusted by inserting spacing shims into the gap between the face of the housing and the confronting surface of the mounting and adjusting ring. It is to be noted in any case that the table plate of the turntable was disposed largely recessed within the housing's bearing area and the mounting and adjusting ring was screwed to the housing. Thus the diameter of the table plate and thus also of the wire bearing is established by the horizontal dimensions of the housing in the bearing area. Between the mounting and adjusting ring and the circumference of the table plate there is also a certain, although narrow, gap through which dirt particles and other contaminants, such as chips, drilling and cooling fluid or the like can penetrate. In applications in which this danger exists, this gap must additionally be covered or sealed off in some suitable manner.